Scientists Seek to Tabulate Mysteries of the Aged

By

Carl Bialik

Updated July 24, 2010 12:01 a.m. ET

When Robert Young was little, he found himself wishing he had gotten to know the elderly people in his life before they died. "I wanted to meet them and stay around them first, because they would be passing away first," Mr. Young recalls. The younger people, he would get to later.

Now Mr. Young's childhood inclination has turned into his profession, as the gerontologist tracks the world's oldest people for a variety of research groups.

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Walter Breuning, the "World's Oldest Man," at his 113th birthday celebration in September in Great Falls, Mont.
Getty Images

His work and that of other researchers' has helped to create a new branch of demography: Statistics about the world's best agers. Though major snags persist in the study of such a rare group of people, it has yielded interesting numbers about how rare it is to live to 110—and how likely those who get there are to reach 111, or beyond.

Much of the work in the area has developed from public fascination with rankings of all kinds. Guinness World Records has tracked the world's oldest people since 1955. Two decades ago, researchers interested in forming their own lists joined together in the Los Angeles-based Gerontology Research Group, which verifies extreme-age claims around the world through birth certificates and photo IDs. Now Mr. Young works for Guinness as its head consultant on checking such claims, and also verifies claims for GRG.

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Among the findings: Uneasy lies the head that wears the crown of world's oldest person. Since Jeanne Calment died at age 122 in 1997, as the oldest person ever to meet Guinness's standards, the title has turned over 17 more times, with no one reaching age 120 and just one person reaching age 118. The world's oldest verified person today, Eugénie Blanchard in the French territory of Saint Barthélemy, turned 114 in February.

There may be older people. About 800 million people, or less than one-eighth of the world's population, live in places that, at the turn of last century, had birth records reliable enough to be trusted, according to Mr. Young. That means the true number of supercentenarians, or people at least 110 years old, could be at least eight times greater than the 75 women and three men counted by GRG as of Wednesday.

Thanks to advances in geriatric care, the number of centenarians is increasing quickly—by 32% in just the past five years in the U.S., according to Census Bureau estimates.

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But some researchers also have found a surprising disconnect between that trend and a decline in the number of people who live to 110. The number of supercentenarians world-wide tracked by GRG has been flat over the past decade. "If the numbers of centenarians are increasing exponentially, the number of supercentenarians should be, too," says GRG co-founder L. Stephen Coles. "But it's not."

Still, the accumulated data have started to solve some mysteries about old age.

One crucial research area is mortality. Since 1825, actuaries have known that mortality rates increase exponentially with age, more or less, not counting gender differences or risk factors such as obesity or smoking. For instance, in 2007, the latest year for which U.S. death numbers by age are available, the chance of dying doubled roughly every nine and a quarter years. Among 52-year-olds, 50 of 10,000 died. The death rate among 61-year-olds was 101 of 10,000.

This so-called Gompertz Law, developed in 1825 by English mathematician Benjamin Gompertz, applies until roughly age 70 or 75, says Sam Gutterman, a director and consulting actuary at PricewaterhouseCoopers LLP. Afterward, mortality rates continue to increase, but more gradually. "The population of survivors tends to be more robust than the group of the deceased," says Jutta Gampe, head of the laboratory of statistical demography at the Max Planck Institute for Demographic Research in Rostock, Germany.

That doesn't mean the ultimate survivors are likely to keep living. But it does mean that mortality rates increase slowly at ages over 100.

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In Italy and France, 100-year-old women have about a two-thirds chance of reaching age 101, according to a database housed at the Max Planck Institute. At age 105, their chance of reaching 106 is just under 60%. Survival rates are around 50% at ages 110, 111, 112 and 113, according to the GRG's records. Then, suddenly, they drop to 30% at 114 and 115—the ages at which most of the world's oldest people have died in the past decade.

Science will have to step in to answer what the statistics can't. There simply haven't been enough verified 114-year-olds to know whether that is a magic number marking a biological barrier to continued survival. Perhaps as more people with better birth records dodge the accidents, lifestyle foibles and diseases that fell their peers to reach triple-digit ages, that greater pool will yield more supercentenarians and more of them will survive the annual existential coin flip that is life after 110.

"The supercentenarians are the crème de la crème," says Thomas Perls, director of the New England Supercentenarian Study, which has enrolled 108 supercentenarians since 1997. "That's why I'm studying them."

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